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Practical Engine Building: Block Preparation

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Block Preparation

18.15

00:00 - Once we get our engine block back from the machinist we can actually begin building our engine.
00:05 But before we start the assembly process, there's still a lot of work that we need to cover off on the bare engine block.
00:12 Before we start doing any of the work on the engine block, it's always a good idea to start by fitting the block to an engine stand as we can see here.
00:21 Fitting the block to an engine stand gives us several advantages.
00:25 First of all it places it at a convenient height to actually work on.
00:29 And also it makes it very easy for us to rotate the block so that we can work on either the deck surface of the block or also the underside of the block.
00:38 While we're going through the preparation as well as the assembly process, we're going to constantly be moving from the top surface to the underside of the engine block.
00:48 With the engine block installed on our engine stand, the next step is to remove any remaining oil gallery plugs so that we've got full access to all of the oil galleries, and this is going to be an essential part to allow us to properly clean out all of the oil galleries.
01:04 Now with our example block here, our Toyota 2JZ, we can see that the oil galleries are actually blanked off with aluminium plugs.
01:13 This is an aspect of the 2JZ engine block design.
01:17 These don't use removable oil gallery plugs.
01:21 And that makes our task a little bit more difficult.
01:24 In this case the engine has already been thoroughly cleaned by the engine machinist and once those oil galleries have been cleaned out, the machinist has made up new aluminium blanking plugs and pressed these into place.
01:37 So at this point there's no work for us to do.
01:40 On the majority of engines however, we'll find that there may be removable oil gallery plugs which are threaded into the engine block, and we can remove and refit these to allow full access to the oil galleries during the cleaning process.
01:55 The next step is to start by tapping or cleaning out all of the threaded holes on the engine block.
02:02 Now on our engine block we have a large number of holes including in this case the holes for our head bolts or head studs.
02:09 All of the external bolt holes on the engine block that may be used for fitting auxiliary components such as alternators, maybe the engine mounts, other bracketry et cetera.
02:20 On the underside of the block we also have the threaded holes for the main bearing caps.
02:25 And what we want to do is ensure that all of these threads are clean and free of debris.
02:31 This is going to mean that when we are installing any of the critical fasteners into the block such as the head studs or main studs, we're going to get a true and accurate torque reading and this isn't going to be affected by excess friction in the bolt hole thanks to debris.
02:49 Now in the case of our Toyota 2JZ block, this is a brand new block straight from Toyota, so it's reasonable to expect that these threaded holes should be clean, free of corrosion and debris, however we're still going to go through the process.
03:04 Now when we are cleaning out any of these threaded holes, what we want to do is make sure that we can clean the holes all the way to the very base.
03:14 And this requires what's known as a plug tap, or a bottoming tap.
03:18 This means that the tap doesn't have a lot of lead in at the base of it and this will allow us to thread the hole or clean the thread all the way to the base.
03:28 Now while there are specific thread cleaning or thread chasing taps available, you can still do a perfectly adequate job using a traditional bottoming tap.
03:39 So let's get started now, we're going to have a look at one of our head bolt or head stud holes, and in this case I'm using an 11 by 1.25 millimetre tap.
03:49 Now it's also a really good idea before we actually try tapping the thread or cleaning the thread, to apply a small amount of cutting oil.
03:58 So in this case the cutting oil's just being applied onto the tap and what this does is it ensures that we're not going to actually damage the threads in the block.
04:08 This allows the tap to be lubricated, and it gives us a nicer finish on the threads.
04:16 So let's just tap that thread now.
04:20 When we're cleaning these threads, what we want to do is move the tap in around about one to two turns and then just back it off a little bit, and this allows any debris to be removed from the threads into the flutes of the tap.
04:34 Let's go down to the bottom of this hole now, and we'll remove the tap.
04:52 So we've reached the base of the hole now and we can just back the tap out and remove it back out of the block.
04:59 When we remove the tap, it's often easier to see the debris that's been collected by the tap.
05:04 In this case even with a brand new block we can see there's a reasonable amount of debris and dirt has been removed during that process.
05:12 Now once we've removed the tap, once we've tapped all of the threads, we also want to make sure we clean out the holes remaining in the block.
05:20 There's still going to likely be some of that debris or dirt remaining in the holes.
05:24 Now the way I go about doing this is to use a brake clean product, spray this into the holes, and then just simply clear them out with compressed air.
05:33 So let's go through that process now.
05:36 What I'm going to do is spray a little bit of brake clean down into the hole, and then we'll just use some compressed air, I'm just going to cover the hole with a rag here just so I don't end up getting sprayed with any debris or brake clean.
05:55 So that's our hole now cleaned and we're ready to install our fasteners or our head studs into that particular stud.
06:03 Obviously we'd simply repeat this over the remaining holes in the engine block.
06:08 The next step of our process is to perform a thorough deburring of all of the engine block surfaces.
06:14 What we're doing here is trying to remove the rough or sharp finish where a machined surface meets the raw finish of the engine block.
06:23 These sharp surfaces can end up presenting stress raises on the block, and it also gives us a surface where if we're not careful, we may end up cutting ourselves during the engine assembly or the engine handling process.
06:36 So what we're going to do here is simply use a die grinder to just break down those sharp edges, and provide a very slight chamfer.
06:43 Now we're not trying to remove very much material, we're just removing that sharp edge.
06:48 So let's do that now.
06:51 So I'm just using a carbide cutting bit on the die grinder here.
06:55 And we'll just run this gently down a sharp surface, where the deck surface meets the front surface of the block.
07:49 So that's a demonstration of the deburring process.
07:52 Once we've completed that we should be able to feel that the resulting surface is now nice and smooth.
07:57 And we're just going to repeat this process on any of the external sharp edges on the engine block.
08:04 While we're still on the deck surface of the block here, it's also a good idea to take some time and chamfer any of the holes on the top of the block.
08:13 This particularly becomes important if the deck surface of the block has been machined, as this can result in sharp edges where the deck surface intersects with the water jacket as well as the oil feed and return holes in the top of the block.
08:28 There's a couple of ways we can do this.
08:31 Of course we can use our die grinder as well.
08:33 But we do want to be very careful if we are going to use the die grinder to ensure that we don't slip and run the die grinder bit across the deck surface of the block, as this can affect the ability of the head gasket to seal.
08:46 Another way we can do this particularly on round holes is to use a deburring tool.
08:52 Now the deburring tool is a tool that looks like this, and all we need to do is run it around the inside of any of the round holes, and it will just break down and remove any sharp edges and provide a gentle chamfer.
09:06 So let's have a look at doing that now.
09:08 What we need to do is place the deburring tool in the hole we want to deburr, and then just gently move it around in a circular motion like this.
09:16 As we do this we'll see that it breaks down any sharp edges in the hole that we're deburring and leaves a nice gentle radius or chamfer on the lead into that hole.
09:28 So we're going to use our deburring tool or our die grinder to remove any of the sharp edges from all of the holes on the top surface of the block.
09:36 Obviously we want to make sure that we don't do anything on the actual cylinders themselves.
09:41 We'll find from the machining process that there is a slight lead in on the top of the cylinders and this helps when we go to install the pistons into the block, it helps guide the piston rings down into the block, so we want to make sure that we don't perform any deburring or any chamfering in these areas.
10:01 Now we're going to spin the engine over and we're going to have a look at some areas where there may be some casting flash on the inside of the engine block, and we're going to look at how we can deal with that.
10:11 When I use the term casting flash, what I'm talking about is excess material that's a result of the casting process when the block was manufactured.
10:20 What we need to deal with or have to deal with here is going to depend on the type of block that we're building.
10:26 And some blocks may have absolutely no casting flash visible and require no work from us, while others may require quite a lot of material to be removed.
10:36 The reason we want to remove any casting flash is under high RPM and high power operation, it's likely that the block will vibrate and flex quite a lot and in some instances this may result in some of this casting flash actually breaking free and going through the engine.
10:54 Obviously this is not what we want and it can result in severe damage to the engine.
10:59 The areas where we're likely to find casting flash will include down the areas where the main journals in the block are cast, and we'll also find some casting flash down inside the block as well.
11:13 So any of these protruding areas, these lines that we can see in the block, these are the areas we want to focus our efforts.
11:20 And what we want to do is smooth and remove that casting flash.
11:24 There's a couple of ways we can do this depending on exactly where the casting flash is, and also how much material we need to remove.
11:33 An easy way is to use a die grinder as we've already seen.
11:36 Another way that we can remove this casting flash and smooth the finish is using a power file.
11:42 So let's have a look at those two techniques being used now.
11:46 For our first demonstration I'm going to use an air die grinder.
11:50 Now in this instance the air die grinder is a little bit more powerful than the battery or electric die grinder I have been using, and this is more suited to the task of removing a lot of material quickly.
12:01 Now I've used a rounded tip carbide cutting bit here, and this is quite important as well because the round tip of my carbide cutter isn't going to leave sharp edges on the block as I'm removing casting flash.
12:15 And sharp edges are something we really want to avoid because these can result in stress raises.
12:21 So let's have a look at the die grinder in action.
12:44 So we can see that using the die grinder allows us to remove the material very easily because of the large size of the carbide cutter it does give a nice round smooth finish which is what we're trying to achieve.
12:55 So in just a few seconds I've managed to remove all of that casting flash.
12:59 Now particularly when we are doing this, it can become quite tempting to continue and polish the inside surface of the block.
13:07 And while there can be come potential advantages in doing so in terms of promoting better oil return down into the sump, this really isn't necessary and it's certainly not what we're trying to achieve here.
13:21 We just simply want to remove any of that casting flash that has the potential of becoming loosened during engine operation.
13:29 Now let's have a look at how we can use a power file to remove the casting flash.
13:39 Now in this case I've got an electric power file, and it's just fitted with a relatively coarse, abrasive material.
13:45 And this will allow me to really quickly and easily remove the material.
13:49 Now one thing that is important to note here is the diameter of the end of the power file, this will limit where we can get into in the block, so in order to do this properly, we really do need to use both a die grinder and a power file.
14:04 Let's see it in action anyhow.
14:30 So the power file as you can see, again allows us to really quickly remove material, this actually gives a finer, almost more polished finish to the surface of the block, depending on the grade of abrasive that we're using.
14:42 Again, we don't need to get too caught up here in trying to get a polished finish on the inside though, it's really not necessary and it's not what we're trying to achieve.
14:52 Now while we've still go our die grinder out, another aspect that we may need to deal with depending on the block we're building is improving the oil flow through the engine block.
15:04 Now as I say this will depend on the engine block we're dealing with.
15:07 In some instances what we may find, that there are galleries cast into the engine block.
15:12 In particular an example here is the front of the engine block on a Mitsubishi 4G63 engine.
15:19 The oil galleries are cast into the block and these have a rough finish.
15:24 There's also a very sharp transition where the oil galleries go from moving vertically up the block, and actually turn into the main oil gallery that runs from the front to the rear of the block.
15:36 Now this sharp edge again doesn't promote good flow.
15:39 And by using our die grinder and spending a few minutes just to smooth the surface of those oil galleries, as well as to transitional radius the transition into the main oil gallery, this can help improve oil flow.
15:53 We will be looking more at this in detail in a separate module.
15:58 Now that we've completed all of the dirty work of grinding and deburring the engine block, we can move on and clean down the engine block thoroughly, ready for assembly.
16:08 Now we cover this in detail in a separate module, so right now what we're going to do is actually jump ahead and work a little bit out of order, and we're going to talk about the painting of the engine block.
16:20 Now this is really going to depend on the block you're dealing with.
16:23 If you've got an aluminium block, chances are you're going to leave the raw aluminium finish and you're not going to be applying a paint finish to the outside of the block.
16:32 If you're dealing with a cast iron block however, we're going to want to provide some kind of protection, otherwise the block surface will end up corroding and rusting over time.
16:43 What I'm going to do here is use a high temperature engine paint.
16:48 These are available from a range of manufacturers.
16:51 And what we want to do is after we've cleaned down the block thoroughly, we want to simply apply two to three coats of this engine paint to the outside surfaces of the block.
17:02 When we're painting the engine block, we do want to be careful that we don't end up with paint in any areas it isn't wanted, such as on the deck surface of the block, perhaps the front cover of the engine block, or inside the cylinders.
17:16 For this reason it's a good idea to mask the areas where we don't want paint, before we go ahead and paint the block.
17:23 If we do end up with any overspray in areas of the block it isn't needed, we can remove this reasonably easily using a product such as brake clean or isopropyl alcohol and a clean rag.
17:35 And it's much easier if we do this immediately after the block is painted, rather than later once the paint is correctly cured.
17:43 While we can't show you the painting process here inside our studio, this should be a relatively straightforward process for anyone who's ever used a can of spray paint before.
17:54 Let's jump ahead and have a look at the finished product.
17:57 So this is the sort of result we should be able to expect from our correctly prepared and painted engine block.